Image forming apparatus

Abstract

An image forming apparatus includes a body casing, a pressing member, a process cartridge, and a drawer. The body casing includes a positioning member. The pressing member is disposed inside the body casing. The process cartridge includes a photosensitive drum. The drawer is configured to support the process cartridge and to move, in a sliding direction orthogonal to an axis direction of the photosensitive drum, between an inside position that is a position inside the body casing and an outside position that is a position outside the body casing. The process cartridge includes an engagement portion and a spring. The engagement portion is configured to be positioned by the positioning member. The spring is configured to be pressed by the pressing member such that the engagement portion is pressed toward the positioning member.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 a body casing including a positioning member; 
 a pressing member disposed inside the body casing; 
 a process cartridge including a photosensitive drum; and 
 a drawer configured to support the process cartridge and to move, in a sliding direction orthogonal to an axis direction of the photosensitive drum, between an inside position that is a position inside the body casing and an outside position that is a position outside the body casing; 
 a belt unit including a belt and configured to move between a contact position in which the belt is in contact with the photosensitive drum and a separated position in which the belt is separated from the photosensitive drum, 
 wherein the process cartridge includes:
 an engagement portion configured to be positioned by the positioning member; and 
 a spring configured to be pressed by the pressing member such that the engagement portion is pressed toward the positioning member, and 
 
 wherein the pressing member is integrally configured with the belt unit, and is configured to contact the spring of the process cartridge when the belt unit is in the contact position and to separate from the spring of the process cartridge when the belt unit is in the separated position. 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein
 the process cartridge includes a sidewall supporting the photosensitive drum, and 
 the spring is disposed on an inner side with respect to the sidewall in the axis direction of the photosensitive drum. 
 
     
     
       3. The image forming apparatus according to  claim 1 , wherein the spring includes two pressed portions that are disposed at an interval in the sliding direction such that the photosensitive drum is positioned therebetween when viewed in the axis direction of the photosensitive drum. 
     
     
       4. The image forming apparatus according to  claim 1 , wherein the pressing member is configured to move between a first position in which the pressing member abuts against the process cartridge and a second position in which abutment of the pressing member against the process cartridge is released. 
     
     
       5. The image forming apparatus according to  claim 4 , further comprising a biasing portion configured to bias the process cartridge supported by the drawer so as to release the engagement between the engagement portion and the positioning member, wherein
 the process cartridge is configured to move between an engagement position in which the engagement portion and the positioning member are engaged with each other and a disengagement position in which engagement between the engagement portion and the positioning member is released, in a state in which the process cartridge is supported by the drawer, 
 the process cartridge is disposed in the engagement position when the pressing member is in the first position, and 
 the process cartridge is disposed in the disengagement position when the pressing member is in the second position. 
 
     
     
       6. The image forming apparatus according to  claim 5 , wherein the biasing portion includes:
 a contact portion configured to contact the process cartridge and move the process cartridge between the engagement position and the disengagement position; and 
 a restriction portion configured to restrict movement of the contact portion such that an amount of movement when the process cartridge is moved from the engagement position to the disengagement position is constant in the sliding direction. 
 
     
     
       7. The image forming apparatus according to  claim 6 , wherein
 the biasing portion includes an advancing/retreating portion including the contact portion and the restriction portion, and 
 the drawer includes a recess configured to accommodate the advancing/retreating portion. 
 
     
     
       8. The image forming apparatus according to  claim 5 , wherein the spring of the process cartridge includes:
 an abutted portion against which the pressing member disposed in the body casing abuts; and 
 a biasing member configured to bias the photosensitive drum towards the positioning member by abutment of the pressing member disposed in the body casing against the abutted portion, and 
 wherein the abutted portion is configured to move, in a first direction in which the photosensitive drum and the belt unit face each other, between an advance position and a retreat position that is farther away from the belt unit with respect to the advance position. 
 
     
     
       9. The image forming apparatus according to  claim 8 , wherein, in the first direction, an amount of movement of the pressing member disposed in the body casing when moving from the first position to the second position is larger than a sum of the amount of movement of the process cartridge moving from the engagement position to the disengagement position and an amount of movement of the abutted portion moving from the retreat position to the advance position. 
     
     
       10. The image forming apparatus according to  claim 8 , wherein the abutted portion includes:
 a cylindrical portion configured to contact the biasing member; and 
 an arc portion configured to contact the pressing member. 
 
     
     
       11. The image forming apparatus according to  claim 8 , wherein the biasing portion includes a spring. 
     
     
       12. The image forming apparatus according to  claim 1 , wherein the pressing member is disposed so as to be aligned with the belt unit in the axis direction of the photosensitive drum. 
     
     
       13. The image forming apparatus according to  claim 1 , further comprising an exposure unit configured to expose the photosensitive drum and disposed such that the process cartridge is disposed between the belt unit and the exposure unit when the drawer supporting the process cartridge is positioned in the inside position, wherein
 the belt has a transfer surface configured to contact the photosensitive drum, 
 the pressing member has an abutment surface configured to abut against the process cartridge, and 
 the abutment surface is disposed so as to be closer to the process cartridge with respect to the transfer surface. 
 
     
     
       14. The image forming apparatus according to  claim 1 , wherein the process cartridge is disposed below the belt unit. 
     
     
       15. The image forming apparatus according to  claim 1 , wherein
 the body casing includes a cover configured to move between an open position in which an opening is opened so as to allow the process cartridge to pass therethrough and a closed position in which the opening is closed, and 
 the belt unit is configured to move from the contact position to the separated position in conjunction with movement of the cover from the closed position to the open position, and to move from the separated position to the contact position in conjunction with movement of the cover from the open position to the closed position. 
 
     
     
       16. An image forming apparatus comprising:
 a body casing including a positioning member; 
 a process cartridge configured to be detachably attached to the image forming apparatus, the process cartridge including a photosensitive drum and a contacting portion; and 
 a belt unit including a belt and a pressing member, the belt unit being configured to move between a contact position in which the belt is in contact with the photosensitive drum and a separated position in which the belt is separated from the photosensitive drum, 
 wherein the contacting portion is configured to contact the belt unit and receive a force to press the process cartridge from the pressing member of the belt unit toward the positioning member, and 
 wherein the pressing member is integrally configured with the belt unit, and is configured to contact the contacting portion of the process cartridge when the belt unit is in the contact position and to separate from the contacting portion of the process cartridge when the belt unit is in the separated position. 
 
     
     
       17. The image forming apparatus according to  claim 16 , wherein the contacting portion includes a spring. 
     
     
       18. The image forming apparatus according to  claim 16 , wherein
 the body casing includes a cover, the cover being configured to open and close an opening configured to allow the process cartridge to pass therethrough, and 
 the pressing member of the belt unit is configured to contact the contacting portion of the process cartridge in conjunction with closing the cover.